What is a craniectomy for decompression?

What is Decompressive Craniectomy?

Decompressive craniectomy is a life-saving neurosurgical procedure that involves removing a portion of the skull and opening the underlying dura to relieve elevated intracranial pressure caused by severe brain swelling from conditions such as stroke, traumatic brain injury, or other causes of cerebral edema. 1

Surgical Technique

For Supratentorial (MCA) Infarction

• A large fronto-parieto-temporo-occipital craniectomy extending to the midline with a diameter of at least 12 cm must be performed 2
• The dura is opened (durotomy) and an enlargement duroplasty is performed to allow the swollen brain to expand outward 2
• Removing ischemic brain tissue is not recommended 2
• If concomitant intracranial bleeding is present, the hematoma can be evacuated 2
• Intracranial pressure monitor placement is recommended 2

For Cerebellar Infarction

• Craniectomy extends up to the transverse sinus with opening of the foramen magnum 2
• Durotomy, enlargement duroplasty, and removal of ischemic cerebellar tissue should be performed (unlike supratentorial infarction) 2
• If concomitant hydrocephalus exists, external ventricular drainage with ICP monitoring or ventriculostomy should be considered 2
• Shunt placement without craniectomy is not recommended 2

Primary Indications

Malignant MCA Infarction (Class I, Level A Evidence)

• Age typically <60 years 2
• Impaired consciousness or progressive reduction of consciousness 2
• Mass effect on brain imaging showing edema exceeding 50% of the MCA territory with midline shift 2, 1
• Exclusion of other causes of impaired consciousness (hypoperfusion, hypotension, cerebral reinfarction, seizures) 2

Cerebellar Infarction (Class III, Level C Evidence)

• Neurological signs of brainstem compression (hypertension, bradycardia, progressive reduction of consciousness) 2
• Mass effect on brain imaging 2
• No age limit is suggested for cerebellar infarction, unlike supratentorial strokes 2

Traumatic Brain Injury

• Refractory intracranial hypertension despite maximal medical therapy 1, 3
• Removal of symptomatic extradural hematoma regardless of location 1
• Removal of significant acute subdural hematoma 1

Absolute Contraindications

• Bilateral, nonreactive, non-drug-induced pupillary dilation associated with coma 2, 1
• Clinical or radiological signs of severe, irreversible brainstem ischemia 2, 1
• Severe comorbidity (severe heart failure or myocardial infarction, incurable neoplasia) 2
• Patient refusal as documented in advance directives or communicated by proxies 2
• Simultaneous presence of all four unfavorable prognostic factors: age ≥50 years, involvement of additional vascular territories, unilateral pupillary dilation, and GCS <8 2

Mortality and Functional Outcomes

Impact on Mortality

• Decompressive craniectomy reduces mortality by approximately 50% compared to medical management alone (26.9% vs 48.9% mortality) 1
• The number needed to treat is approximately 2 to prevent one death 1
• In patients >60 years with MCA infarction, 1-year mortality is reduced from 69.6% to 16.7% 2

Functional Outcomes and Disability

• Nearly all survivors suffer residual permanent disabilities 2
• At 12 months post-injury in TBI patients, 45.4% of decompressive craniectomy patients had favorable outcomes versus 32.4% with medical management alone 1
• In patients >60 years with MCA infarction, 1-year poor outcome (mRS >4) is reduced from 100% to 37.5% 2
• The procedure is associated with higher rates of vegetative state or severe disability compared to medical management, despite lower mortality 3

Timing and Preoperative Management

Optimal Timing

• Surgery should be performed as fast as possible once clinical and radiological criteria are fulfilled 2
• Early intervention before clinical signs of brainstem compression develops yields better outcomes 1
• All randomized studies involved intervention within 48 hours of neurological deterioration 2

Bridging Measures if Surgery is Delayed

• Profound sedation, analgesia, intubation, and controlled mechanical ventilation with target PaCO2 of 35 mmHg 2
• Placement of central venous and arterial catheters 2
• Osmotherapy (mannitol 20%, hypertonic NaCl-HAES solution, or hypertonic NaCl solution) with target serum osmolality of 300-310 mOsmol/kg, though efficacy is controversial as it may aggravate midline shift 2

Coagulation Management

• Coagulation disorders must be corrected before craniectomy 2
• Craniectomy after thrombolysis is possible for either ischemic or hemorrhagic mass effect 2
• At time of surgery, coagulation factors should be in normal range, particularly fibrinogen 2
• If patient received antiplatelet drugs, preoperative platelet transfusion should be considered 2

Postoperative Management

ICU Monitoring

• ICP and cerebral perfusion pressure (CPP) monitoring with maintenance of CPP >60 mmHg 2, 1
• Control CT after 24 hours or earlier if signs of intracranial hypertension are present 2
• Waking from sedation should be attempted only when there are no more signs of significant intracranial hypertension 2

Complications to Monitor

• Wound dehiscence, typically near the posterior aspect of the large craniectomy flap 2, 4
• A substantial proportion of patients may require tracheostomy and gastrostomy 2
• Communicating hydrocephalus may develop if bone flap replacement is delayed, requiring ventriculoperitoneal shunt placement 2, 4

Cranioplasty Timing

• Complication rate (hydrocephalus, infection) is slightly higher with early cranioplasty (within 10 weeks of craniectomy), particularly in patients with ventriculoperitoneal shunt at time of cranioplasty 2, 4

Key Technical Factors for Success

• A large bony window of ≥12 cm in diameter is essential 2
• Dural relaxation with large dural augmentation graft is important for ICP reduction 2
• Young patients with very large infarcts (>400 cm³) may benefit from temporal lobectomy and even reoperation if brainstem decompression is inadequate 2